Area Forecast Discussion
Issued by NWS Cheyenne, WY
Issued by NWS Cheyenne, WY
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600 FXUS65 KCYS 272100 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 300 PM MDT Mon May 27 2024 .KEY MESSAGES... - Potential for some dry thunderstorms capable of producing strong, and sudden wind gusts possible across the I-80 corridor tomorrow afternoon. - Chances for an active weather pattern with organized strong to potentially severe afternoon thunderstorms possible Wednesday afternoon/evening and possibly again on Thursday. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 208 PM MDT Mon May 27 2024 Not much to write about in the short term forecast period as the weather conditions will be quiet and dry today and again tomorrow. Much of the region today is under a modest NW flow aloft with surface temperatures climbing into the 70s across much of the region. Visible satellite just shows some fair weather cumulus clouds beginning to develop across the region this afternoon. Temperatures will warm a few more degrees through the afternoon hours under mostly sunny skies. Another warm day is on tap for tomorrow as an upper level ridge builds into the region allowing for warmer 700mb temperatures to advect into the region. Could be a weak disturbance embedded in the mean flow coming through Tuesday afternoon underneath the main ridge axis and this feature could be strong enough to help initiate some isolated thunderstorms across the I-80 in SE Wyoming by the late afternoon hours. Atmospheric parameters show minimal CAPE and shear available, but storms that do develop will be high based with a decently dry sub cloud layer yielding some 1000 J/kg of DCAPE which poses an increasing microburst type wind threat with storms that manage to develop. Additionally these storms may be the dry thunderstorm variety which may pose a locally fire weather concern. Outside of that much of the region should see warming temperatures and a continuation of dry and quiet weather. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Issued at 208 PM MDT Mon May 27 2024 Wednesday afternoon appears to be one of our most active weather days this week in response to a shortwave moving through the northern Rockies. This should allow for a good moisture feed mainly east of the Laramie range where dewpoints could pool in the 50s which may yield surface based cape values into the 2000-2500j/kg Wednesday afternoon/evening. The National Blend of Models is showing lower probabilistic values since it leaning towards the drier Global solutions. For now, we are favoring the mesoscale NAMNEST which shows more support towards the higher dewpoints. The main question will be the lifting mechanism. Deterministic models are showing some signs of potential vorticity moving through the area with upper level diffluence. However, not seeing as much influence from the upper level jet. Therefore, most of these storms could end up being more induced along the sudo dry line or orographics. Either way, if we do see a few storms develop along the Laramie Range, they stand a pretty good shot of becoming strong to severe east of the I-25 corridor, due to the combination of high thetae air and 30 to 40kts of effective shear. The models are projecting the frontal boundary and another stronger shortwave moving through the forecast are on Thursday. The main question is whether there will be enough moisture recovery from the previous night`s convection. For now, the latest GFS/ECMWF are showing the bulk of the convection developing east of the Nebraska panhandle. Another concern is the potential for gusty winds developing behind the front Thursday over areas west of the Laramie Range. This could set the stage for potential wind headlines near Arlington Thursday, but it should be rather shortlived especially if the subsidence is rather minimal. Otherwise, cannot rule out a few isolated showers and thunderstorms unless the moisture does not scour out from the previous day. Friday-Monday: The WPC clusters are showing the upper level flow transitioning to a more flatter regime as we head into the weekend. Meanwhile, the GFS is still the outlier in showing a deep upper level trof developing over the area. If the GFS pans out we could end up with much cooler temperatures with continued chance of showers and thunderstorms. At this point, we are leaning towards the ensembles which is favoring mild temperatures with scattered showers and thunderstorms mainly in the Nebraska panhandle on Friday and isolated showers and thunderstorms this weekend into early next week. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 515 AM MDT Mon May 27 2024 A quiet TAF period is expected as a ridge of high pressure builds over the region. Mostly sunny skies and diurnal wind gusts up to 25 kts are expected this afternoon. Winds will ease this evening with mostly clear skies continuing overnight. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...AW LONG TERM...REC AVIATION...SF